Potential for the Use of Rhizobacteria in the Sustainable Management of Contaminated Soils

Abstract

The removal of contaminants from the environments has become a crucial problem that requires a variety of approaches to reach suitable solutions. This review will focus on the use of rhizobacteria for restoration of sites cocontaminated with organic pollutants and heavy metals. While the first contaminants can be biodegraded to innocuous end products, metals are not biodegradable and must either be removed or stabilized within the site. Plant growth promoting rhizobacteria (PGPRs) represent a wide variety of soil bacteria which, when grown in association with a host plant result in stimulation of growth of their host also in a stressed environment. Plants, especially dicotyledons that are treated with ACC deaminase-containing PGPRs are more resistant to the deleterious effects of ethylene synthesized as a consequence of stressful conditions. In this review the use of PGPRs to assist plants in remediation processes is examined by discussing recent advances in bioaugmentation efforts. The effectiveness of the external manipulation of rhizosoil to overcome physical and chemical constraints to root establishment and to enhance pollutant removal is also examined. Finally, it is provided a summary of the recent advances in the potential for the use of transgenic plants and/ or microorganisms to remediate environmental contaminants. The complexity and diversity of plant/soil/microorganism systems require an integrated approach involving basic and applied researches in order to establish phytoremediation as a viable and attractive technology for efficient restoration of co-contaminated soils